Current-regulator.



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CURRENT REGULATOR.

APPLICATION HLED JUNE 2l, 1912.

Patented Dec. 18, 1917.

3 SHEETS-SHEET 2- WITNESSES: INVENTOR I 951mm C. LE G. FORTESCUE. cusmenREGULATOR.

'l APPLICATION FILED )UNE 2| 1912- v 3 SHEETS-SHEET 3- vENToR UNITEDSTATES PATENT CHARLES G. FOBTESCUE, OF PITTSBURGH, PENNSYLVANIA,ASSIGNOB T) WE'STING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, ACORPORATION OF .PENNSYL- VAN IA.

CURRENT-REGULATOR.

Specification of Letters Patent.

To all whom t may concern.'r

Be it known that I, CHARLES LE' G. FOR- Tnsonn, a subject of the King ofGreat Britain, and a resident of Pittsburgh, in the county of Alleghenyand State of Pennsylvania, have invented a new and useful I mprovementin Current-Regulators, of which the following is a specification.

My invention relates to constant-current regulators and to systems ofdistribution embodying the same.

The object of my invention is to provide a constant-current regulatorfor use `on an alternating current circuit that is of such aconstruction as to permity of its ready adaptation to a great variety ofuses and un# der widely varying conditions, while, at the same time, itis simple in construction, economical to manufacture and efiicient inoperation, having low internal losses, vespecially under no-loadConditions.

In its simplest form, the present regulator is employed in combinationwith a voltage-changing transformer, in connection with any alternatingcurrent circuit in which it is desired to maintain a constant current,such as a series of incandescent street lights, and, at the saine time,effect a proper voltage transformation. When thus designed, it maysupply constant current to any alternating current circuit, or to acurrent rectifier. When employed for supplye ing current to rectiiers,it may also adapted to provide the proper amount of sustaining ei'ectfor the rectified current, as well as to supply several rectiiers at thesame time either in seri-es or in parallel. It

-may furthermore be readily adapted yto supply dierent values ofconstant current.

Figure 1 is a diagrammatic view of a simple form of regulator that isillustrated to assist in explaining the operation of the regulator of mypresent invention. Fig. 2 is a view of a regulator embodying a form ofmy invention and adapted to e'ect voltage transformation. Fig. B-is asimilar view of a regulator of the kind shownin Fig. 2, but adapted tosupply current to a rectifier. Fig. 4 illustrates a regulator adapted tosupply constant current to a'rectifier and, at the same time, to providethe proper amount of sustaining effect for the rectified current. Figs.5 and 6 are diagrammatic views of modified forms of regulator that areadapted to supply current to a plurality 'of rectifiers, the rectiliersbeing connected in series Patented Dec. 18, 1917.-

in Fig. 5 and being independent in Fig. 6.

Fig. 7 is a plan and sectional View, and Fig. 8 1s a side and,diagrammatic view of a modified form of regulator which is adapted tosupply current to a plurality of parallelconnected rectiiiers. Y

The regulator of Fig. 1 comprises a magneti'zable core member 1 of anysuitable form, here shown of the shell type with two movable coils 2 and3 surrounding the middle leg thereof, 'the said coils having the samenumber ofconvolutionsand being connected to produce fluxes in oppositedirections in the core member. The movable coils are carried by cablesor chains 4 and 5 that pass over sheaves or pulleys 6 and 7respectively, one end of the chain 5 being connected to one side of thecoil 2 and the other end being .connected to the opposite side of thecoil 3, and the chain 4 being connected in the reverse manner. The coil2 is weighted so as to be somewhat heavier thanthe coil 3 in order thatthe said coils may be close together when no current traverses them. Thecoils 2 and 3 are connected in series relation and they may also beconnected directly in the circuit. in which it is l desired to maintaina constant current such, for instance, as a series circuit ofincandescent street lights 8, as indicated in 1. In this instance, aseparate transformer may be employed in combination with the regulatorfor obtaining a suitable voltage or current transformation.

In the operation of the reo'ulator, the coils 2 and-3 will be closelyadJacent when the effective impedance or back electromotive force of theload is highest, but for intermediate values of these quantities theyvwill occupy positions such that the current will be maintained constantwith varying load reaction or back electromotive force, or, in otherwords, the virtual impedance of the primary circuit is maintainedconstant by the repulsion of the coils for all values of the loadimpedance or back electromotive force. Consequently, at light loads thecoils will be far a art, and at heavy loads close together. en the coilsare close together, very little induction passes through the los middlecore leg, whereas, when they are l l most widely separated, theinduction in the middle leg is comparatively large. Where 1t isnecessary to employ a translegs of the core member.

former for effecting the proper voltage or current transformation, it isdesirable, for the sake of economy, to combine the means foreffectingsuch transformation with the regulator. This is done in Fig. 2,in which the middle leg of the magnetizable core is surrounded byprimary and secondary coils 10 and 11 which are placed in closeinductive relation and are employed for the purpose of effecting voltagetransformation, current being supplied from the secondary Winding to anysuitable circuit 12, such as a series of lamps. The middle core leg isalso surrounded by the movable regulator coils 13 and 14 the same as inFig. 1, the said coils being connected in series with the primary coil10 and being otherwise connected and arranged as in Fig. 1. The coils 10and 11, being in close inductive relation, the desired voltagetransformation will be efficiently obtained while, at the same time, themovable regulator coils 13 and 14 will introduce 'the proper reactanceinto the primary circuit for the purpose of maintaining the current inthe secondary circuit substantially uniform.

It is important, in order to insure efficient operation of theregulator, that the two movable coils 13 and 14 be connected in seriescircuit with the primary coil 10 of the potential transformer. Underno-load conditions, the movable coils 13 and 14 are separated from eachother the maximum distance, and the entire potential drop in the primarycircuit is consumed in overcoming the impedance of the two movable coilsbecause, in this position, the leakage reactance' between the coilsreaches its maximum value. In consequence thereof, the leakage fluxpasses from the central core leg between the two coils, divides into twopaths and flows in opposite directions in th outer core As a result, thecore is uniformly magnetized to a low degree which insures eflicientoperation of the regulator, or, in other words, very low noload losses.If one of the movable coils were connected in circuit. with the primarywinding and the other in circuit with the secondary winding, ashas beenheretofore proposed, the primary winding, under noload conditions, woulddivide the potential of the line, with the movable coil connected incircuit with it, and, consequently, an uneven flux d1str1but1on 1n thecore member would obtain, subjecting portions of thecore member to avery high degree of magnetization and other portions to arelatively lowdegree of magnetization. The uneven flux distribution within the corewould in.- crease the no-load losses appreeiably.

In Fig. 3, a regulating and transforming device similar to that of Fig.2 is employedl for the purpose of supplying a constant amount of currentto a current-rectifying device 15, here shown as of the mercury vaportype, though any other suitable form may be employed. In this device,the secondary winding comprises four coils 16,

y 17, 18 and 19, respectively, two surrounding the upper end of themiddle leg of the core and two the lower end thereof, the primary coils2() and 21 being interposed between the two secondary coils at each endof the leg of the core and extending from end to end thereof. The objectof this arrangement of the coils is to separate from each other thesecondary coils that supply alternate half waves of current to therectifier, so as to reduce the mutual induction, and to thereby providefor a large amount of leakage, between the coils. This leakage takes theform of a pulsating inductional flux, its effect being to introduceinertia `into the system, similarly to a fiy wheel in a mechanicalsystem. In order to provide for a greater sustaining effect for therectified current, it is also desirable to employ a reactance device 22in" series with the load that is supplied from/ the rectifier.

Another form of the device that is adapted to supply current to acurrent-rectifying device is shown in Fi 4, in which only the movableregulator coils 24 and 25 surround the middle leg of the core member,and the outer legs are respectively'surrounded by primary coils 26 and27 and secondary coils 28 and 29, the primary coils being connected inseries with each other and with the regulater coils 24 and 25, as in thepreviously described devices. The an-odes of a currentrectifying device30 are respectively connected to terminals of the secondary coils 28 and29 and the cathode is connected to the remaining terminals thereof.

With this form of the device -it is unnecessary to employ an additionalimpedance device for. the purpose of sustaining the rectified current,since the desired amount alternate half cycles. When the flux in the Ycore has a direction indicated by the arrows 32, the secondary coil 28lis'active and the primary fiux is opposed by the counter-fiux of thesaid secondary coil, which is indicated by the broken lines 34 which hasa direction indicated by the arrows During the next half cycle, thesecondary coil 29 is active and the primary flux, which is Landsatindicated in direction by the arrows 33, is opposed by the counter-iuxindicated by the broken line 36, which has a direction indicated by thearrows 37. It will be noted that the counter-fluxes indicated by thebroken lines 34 and 36 traverse the central leg of the core in the samedirection. The etl'ect of this unidirectional flux is the same as thatdue to the introduction of inductance into vthe direct current circuitof the rectifier, that is to say, it introducesinertia into the systemwhereby the current pulsations are reduced to a small value. Thisreactance is adjusted to the proper value by providing the central legof the core member with an air gap indicated at 38,. IThe provision ofthis air gap does not impair the regulation afforded by the movablecoils 24 and 25, since the fluxes produced by the said coils oppose eachother, and consequently, they are not effective to send flux through themagnetic circuit in the same direction. As in the preceding regulators,the liux due to the regulator coils 24 and 25 is low when the load ishigh, and, under such conditions, the middle leg of the core will betraversed substantially only by the sustaining tluX. Since thelsustaining flux always traverses the middle leg of the core in the samedirection, it first supplements and then opposes the working flux in thecore, the result through a whole cycle being the same as if theregulator coils were not employed at all.

It will, of course, be understood that, if desired, each half of thesecondary winding may be divided into two or more parts and may comprisetwo or more coils, which may be connected in series or in parallelrelation for the purpose of adapting the device to supply differentamounts of current, or for the purpose of permitting the employment ofthe device in connection with two or more current rectifiers. The mannerin which the device will be constructed for such purposes and in whichthe connections should be made will be readily understood from themanner in which transformers are usually constructed and connected Jforsimilar purposes, and it is, consequently, deemed unnecessary toillustrate the same.

When current is to be supplied to a plurality of current rectifyingdevices, I prefer to construct the regulating and transforming device asillustrated in Figs. 5 and 6, in which the core member is provided witha central leg 40 and a plurality of outer legs 41, 42, 43 and 44, thecentral leg being surrounded, as usual` by the movable regulator coils45, and each of the outer legs being surrounded by primary and secondarycoils 46 and 47, respectively. The primary and secondary coils may beconnected in many suitable and practical arrangements, but, in

Fig. 5, the primary coils surrounding the legs 41 and 43 are connectedin series, and

also the primary coils surrounding the legs 42 and 44, andthe twoseries-connected pairs of coils are connected in parallel relation andin series with the regulator coils 45. The connections of the rectifyingdevices to the secondary coils are such that the rectified currentpasses through the rectifying devices in series. To this end, the anodesof the rectifier 48 are respectively connected to terminals of thesecondary coils surrounding the core legs 41- and 43, and the anodes ofthe rectifier 49 are respectively connected to terminals of thesecondary coils surrounding the legs 42 and 44, while the cathode of thedevice 48 is connected to the remaining terminals of the coilssurrounding the legs 42 and 44, and the cathode of the device 49 isconnected to the remaining terminals of the coils surrounding the legs41 and 43, the translating devices to which the current is suppliedbeing preferably included in the latter connection. In some instances,it may be desirable to provide the middle leg 40 of -the core with anair gap.l

In Fig. 6, the primary coils are all connected in series relation and inseries With the movable regulator coils, and current is supplied fromthe secondary coils to two independent rectifying devices 50 and 51,each supplying its own circuit. The secondary connections are similar tothose of Fig. 5,"

except that the cathodes of the rectiiers are connected through thetranslating devices to the remaining terminals of the same secondarycoils as those to which their anodes are respectively connected.

In Figs. 7 and 8, a modified form of a regulating transformer is shownsimilar to that of Figs. 5 and 6 but adapted to provide a large amountof inductance opposed to the flow of current in the rectifiers upon theoccurrence of short circuits therein. The general form of the coremember is similar to that of Figs. 5 and 6, but comprises four similarrectangular portions each comprising two legs, and each similar in shapeto the core of a core-type transformer. The four core portions areplaced with one leg of each adjacent as shown in Fig. 7 to form anassembled core having a middle leg and four outer legs, the middle legbeing surrounded by the movable regulator coils.

The coils 52, 53, 54 and 55, which sur-y round the outer legs of thecore, are connected in series in pairs, one .pair comprising the coils52 and 55, and the other pair comprising the coils 53 and 54. Both pairsare then connected with each other in parallel relationship and inseries with the regulator coils. This form of connection is similar tothat shown and described in detail in connection with Fig. 4 where onepair of coils only is'connected in series with the regulator coils. Oneterminal of each of the secondary coils 56 and 57, which aresimultaneously influenced by the divided currents owing infthe coils 52and 53, respectively, are connected to the respective anodes of thecurrent rectiier 60, the other terminal of each of said secondary coilsbeing connected, through the lamp circuit 62, to the cathode of therectifier 60. Similarly, one terminal of each of the secondary coils 58and 59, which are simultaneously influenced by the divided currentsflowing in the coils 54 and 55, respectively, are connected to therespective anodes of the current rectifier 61, the other terminal ofeach of said secondary coils being connected, through lamp circuit 62,to the cathode of the rectifier 61. The coils are so wound that themagnetic fluxes generated by the secondary coils 56 and 59 during onealternation, and the coils 57 and 58 during the other alternation of theprimary current wave, flow through the middle leg of the core in thesame direction. The effect of this unidirectional linx through the coreleg embraced by the regulating coils is the same as that which obtainsby introducing an inductive-reactance element in the direct-currentcircuit of the rectifier, as eX- plained in connection with the deviceof Fig. 4. To obtain further sustaining effect, two impedance devices 63are connected in the leads extending from the cathodes of therectifiers. If, with this arrangement of connections, a sho'rt circuitoccurs in the recti- {ier 60, for instance, the short circuit currentwill traverse secondary coils 56 and 57 and induce currents in thecorresponding primary coils. The current induced in the primary coil 53is thus combined with the current in the primary coil 52 to produce adistortion of the wave form of the primary current. This gives the eiectof a high inductance in each branch of the parallel connection in seriescircuit with the regulator coils, thereby limiting the flow of theshortcircuit currents.

I claim as my invention 1. A regulator comprising a core, primary andsecondary windings thereon, and movable coils surrounding a part of saidmember and connected in series with the primary winding.

2. A regulator comprising a core, primary and secondary windingsthereon, and movable coils surrounding a part of said member andconnected in opposition to each other and in series with the primaryWinding.

3. A regulator comprising a core, primary and secondary windingsthereon, movable coils surrounding a part of said member and connectedin series with the primary winding, and counterbalancing means for themovable coils.

4. A regulator comprising a core, primary and secondary windingsthereon, movable coils surrounding a part of said member and connectedin opposition .to each other and in series with the primary winding, andmeans for causing the movable coils to move simultaneously andcorrespondingly.

5. A regulator comprising a core, primary and secondary windingsthereon, and mov able coils having substantially equal numbers ofconvolutions surrounding a part of said member and connected inopposition to each other and in series with the primary winding.

6. A regulator comprising a core member having a central leg and aplurality of outer legs, primary and secondary coils upon the outerlegs, and movable coils upon the central leg that are connected inseries-circuit relationship with said primary coils.

7 A regulator comprising a core member having aI central leg and aplurality of outer legs, primary and secondary coils upon the outerlegs, and movable coils upon the central leg connected in opposition toeach other and in series with the primary coils.

8. A regulator comprising a core member having a central leg and aplurality of outer legs, a primary coil and a secondary coil upon eachouter leg, and movable coils upon the central leg connected inopposition to each other and in series with the primary winding.

' CHARLES LE G. FoRTEsoUE.

Witnesses:

O'r'ro S. SCHAIRER, B. B. HINEs.

